1. Field of the Invention
The present invention relates to a new and improved lever arm assembly and more particularly to one including a thin flat lever arm adapted to be detachably mounted on a rotary shaft of a door closer or the like. Many swinging door applications have a need for a relatively thin flat lever arm extending between the shaft of the door closer and a slide which is mounted on the upper edge of the door. The vertical space available for a lever arm of a door closer is often extremely limited and additionally, problems have been encountered because of the difficulty of securing a thin flat arm onto a rotary shaft at right angles thereto in a manner sufficient to withstand without failure the repeated and reversing stress applications because of the high torque involved. Often times premature failure of the arms occurred at the region of attachment on the shaft.
2. Description of the Prior Art
Prior art door closures have utilized closer arms which were often formed of cast material and the end of the arm attached to the door closer shaft has proven to be a source of difficulty because of the enlargement in size needed on this portion in order to successfully withstand the repeated high stress torque applications caused during opening and closing of the door. Failure of prior arms of cast material is generally in the regions or areas of high stress application around the walls of the key-shaped openings in the enlarged end portion of the arm into which the shaft of the door closer is interfitted. Closer arms formed of cast material additionally have the disadvantage of requiring more space in a vertical direction because of the enlarged section modulars needed in order to reduce the stress application to an acceptable design limit. Prior art cast type closer arms require machining operations and thus, are relatively high in cost and are often difficult to mount and dismount from the shaft.
It is therefore an object of the present invention to provide a new and improved arm assembly adapted to be detachably mounted on a rotary shaft such as the shaft of a door closer or the like.
Another object of the present invention is to provide a new and improved lever arm assembly of the character described which employs a novel system for positively securing the arm to the shaft without requiring excessive depth or thickness of the arm.
Another object of the present invention is to provide a new and improved lever arm assembly of the character described which employs a hub or wedge plate which is adapted to rotate relative to the arm when fasteners are applied to secure the hub on the arm and the assembly in place on the shaft.
Yet another object of the present invention is to provide a new and improved lever arm assembly of the character described wherein the parts are formed from thin flat metal in stamping operations rather than being formed of cast material.
Another object of the invention is to provide a new and improved arm assembly which presents a neat, thin, flat appearance in elevation compatible with modern doors.
Yet another object of the present invention is to provide a new and improved lever arm assembly of the character described wherein a novel wedging or camming action is provided by the attachment of a hub or wedge plate for securing the arm in place on the shaft and which results in a scissors-type pinching action holding the arm securely on the shaft while requiring a minimum of shaft length.
Another object of the present invention is to provide a new and improved lever apparatus of the character described which is easily detached from and/or remounted upon the rotary shaft of a door closer or the like so that servicing and maintenance is enhanced.
Yet another object of the present invention is to provide a new and improved lever arm which is neat in appearance, economical to produce and easy to install, and which is suitable for most all door closer applications.